I had (have) a problem with skin irritation caused, I think, by the hair conditioner used to lube the suit. I've done some searches through DB and found various different suggestions, I'm currently trialling a product called J-Lube, it's a veterinary lubricant used during internal examinations. It's quite difficult to come by and I ended up buying it from an online fetishist store for £18 a tub. It comes in powder form and a tiny amount creates lots of slime. I found it very slippery, though it tends to clump together rather than coat the inside of the suit, I now mix a tiny amount of baby shampoo with it and it tends to break down and will coat the suit nicely. The irritation is significantly reduced, if not totally gone. Now I just need to deal with the issue of pissing in my suit, maybe get a pissette fitted.
Good luck